[Truncated abstract] Limitation of sagittal plane dorsiflexion, or hallux limitus (HL), represents the second most commonly encountered pathomechanical disorder affecting the first metatarsophalangeal joint, after hallux valgus (HV). The kinematic role of the first metatarsophalangeal joint represents an integral component of the gait cycle. It has often been reported that for adequate leverage and propulsion to occur during normal gait, the hallux must be able to dorsiflex approximately 65° on the head of the first metatarsal. Secondary gait compensation mechanisms have often been observed clinically as a result of HL. The effect of HL on gait can be reflected in transverse plane alteration of the foot in relation to the line of progression during gait, defined as the angle of gait (AOG). The first purpose of this study served to investigate potential differences in dynamic angle of gait AOG in subjects with HL compared to a control group. A validated technique using coloured powdered footprints was used to quantify AOG. Furthermore, it was required to establish whether the relative amount of transverse plane motion observed in the AOG was related to factors intrinsic or extrinsic to the foot. Intrinsic factors such as the amount of forefoot to rearfoot abduction was considered, and achieved by measuring the rearfoot to forefoot axis (RFA) angle using a weight bearing composite (COMP) view radiograph. The remaining objectives of the study served to investigate other common aetiological factors associated with HL and their potential influence on AOG in subjects with HL ... Results further indicated that the amount of first metatarsophalangeal joint dorsiflexion did not appear to influence AOG in the two groups, and that AOG did not reflect the iii amount of forefoot to rearfoot abduction in a foot with HL compared to the control group. When comparing foot type, as indicated by CIA, it appeared AOG did not significantly alter between the HL and control groups. Finally, the results indicated AOG did not differ significantly between subjects with unilateral HL. This thesis study indicated that with the current sample population, the wide variability in AOG prevented detection of any subtle differences that may exist in subjects with HL. Results also emphasised the need to incorporate other variables such as symptomology and foot dominance when considering the effects first metatarsophalangeal joint pathology might have on HL, such as AOG.

[Truncated abstract] Hallux valgus (HV) is one of the most common foot deformities encountered in clinical practice. This complex deformity primarily affects the first metatarsophalangeal joint (MPJ), leading to altered foot structure and function. By virtue of the lateral displacement of the hallux on the first metatarsal, HV has the potential to influence adjacent joints of the foot. In doing so, function of the foot may be altered, and clinically this may result in abduction of the foot during the stance phase of gait. However the relationship between an abducted angle of gait (AOG) and HV has never been substantially examined. The purpose of this study is to investigate the relationship between HV and AOG, and determine if specific radiographic features are associated with the deformity or with a particular AOG. Such information would assist in understanding aetiological factors and the effects of intervention to treat the deformity ... Length and elevation of the first metatarsal were associated in subjects with HV, implying that length of the metatarsal may be related to whether or not it becomes elevated (R: 0.50, CI: 0.21, 0.71, P< 0.05). Similarly, an association was found between length of the first metatarsal and the amount of first MPJ dorsiflexion, suggesting perhaps length of the metatarsal has implications for first MPJ range of motion (R: -0.37, CI: -0.62, -0.04, P<0.05). However the amount of first MPJ dorsiflexion did not influence the AOG in HV subjects when compared to the control group. First MPJ dorsiflexion was also associated with the first intermetatarsal angle. Interestingly, the HV group alone did not show an association between the hallux abductus angle and the first intermetatarsal angle. The findings of this study are contrary to those suspected in clinical practice and alluded to in the literature. Despite the documented support for the biomechanical causes of HV, an abducted AOG was not significantly different in HV subjects when compared to controls. Possible explanations may have related to limitations of the present study including the size and gender demographics of the sample population, and greater variability in normal AOG ranges than reported in the literature. The present study indicated a possible need to gather information regarding foot dominance and leg length; factors extrinsic to the foot capable of influencing transverse plane orientation of the foot; and, the influence of symptoms and subsequent compensatory mechanisms adopted during gait.